I am always in favor of fresh ingredients when possible. I recently discovered that minced (and crushed and chopped) garlic is available in very inexpensive jars in the produce section of the grocery store. I've always bought garlic and chopped it for a given meal, but I wonder if such jars of prepared garlic are worthwhile.

Would purchasing prepared garlic in a jar be a time saver in some situations, or is the quality reduced such that it is not recommended?

As a side question, does minced garlic in a jar keep for very long once opened?

Agree, with the caveat that a seemly-obvious thing to do, storing fresh garlic in olive oil in the fridge, is a great way to grow botulism bacteria! Unlike things like sun-dried tomatoes, which are acidic and safe to store in oil, garlic is neutral and is a perfect site to grow anaerobic bacteria. If you want to use chopped garlic in the fridge, buy it from a company that knows what additives to use to make it safe.
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HarlanJul 18 '10 at 23:41

You can also just peel it and throw the whole cloves in the fridge to save some of that time. If you've got a garlic press, or you like to grate it as hwillow suggested, the peeling might be the most time-consuming part.
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Jefromi♦Jan 18 '11 at 17:49

I think fresh garlic is much more flavorful! I tried the jarred garlic before, and I could definitely taste a difference. Yes, it's more convenient, but it's not as strong as fresh. A hand grater is useful when using fresh garlic. You won't have to chop and it helps prevent biting into larger pieces.

Sometimes, particularly for a saute or other pan-cooked dish, I want the flavor of garlic, but I don't necessarily want to bite in to it. I'll cut the garlic into thick slices, or just smash it and throw it in whole, with the intention of removing it before serving.

In my experience, fresh garlic is great for when you want texture, or to slow down the flavour infusion. For example, when baking potato chunks, I put fresh garlic in, and then the flavour doesn't take over the entire dish.

For other times, especially recipes that call for minced garlic, I have a jar of frozen crushed garlic that I bought at my local grocery.
I'm not sure what's available where in the world, but in my area, the frozen garlic is cheap and has no additives in it at all.

Generally, one heaped teaspoon of frozen crushed garlic is equivalent to an average garlic clove.

On the other hand, for those times when you do want fresh garlic, a few drops of lemon juice on your hands afterwards and a quick rub will get the garlic smell off your fingers.

I believe one cannot taste the difference between minced(canned) and fresh garlic once it is cooked. Especially if it's been stewed for hours in a slow cooker) So if I want a lot of garlic in my stew, I use minced one and save time!